A power module is used for an electronic apparatus (such as an in-vehicle equipment or an industrial equipment) which requires a switching with large electric current. As to the power module, an electric connection therein is performed by a plurality of wires. Furthermore, in order to prevent a short circuit due to contact between adjacent wires or to prevent degradation due to change of an environment such as moisture, a silicon gel covering the wire is potted in a housing of the power module.
However, under the environment in which a strong external force continually acts on the electronic apparatus, the silicon gel in the housing vibrates by an inertial force. By this vibration, an internal stress repeatedly acts on the wire. As a result, a bonding part between the wire and another part is often broken. Accordingly, in order to maintain a performance or a safety of the power module, improvement of reliability of electrical connection of the wire is desired.